I looked up and called the court
In what county?
I think that he has been to court.
Been to court for what purpose? I've "been to court" hundreds of times, but you won't find any cases under my name. Why do you "think" this person "has been to court," and isn't it possible that the person went to court in a different county than the one you called? Also note that many counties have different branches.
Is there a sure fire way to tell if someone has had a court hearing?
Yes, and it varies from county to county and, in some counties, branch to branch. California has 58 counties, and their websites are not at all unified. In some counties, you can run searches by name, but it many counties (including two of the state's three most populous counties), you cannot.
If the clerk in the county where you called actually checked a name index and told you there was no criminal case involving the person in question, then you seemingly have your answer.